Magnetoresistive-based devices, spin electronic devices, and spintronic devices are synonymous terms for devices that make use of effects predominantly caused by electron spin. Magnetoresistive-based devices are used in numerous information devices to provide non-volatile, reliable, radiation resistant, and high-density data storage and retrieval. The numerous Magnetoresistive-based devices include, but are not limited to, Magnetoresistive Random Access Memory (MRAM), magnetic sensors, and read/write heads for disk drives.
Typically an MRAM includes an array of magnetoresistive memory elements. Each magnetoresistive memory element typically has a structure that includes multiple magnetic layers separated by various non-magnetic layers, such as a magnetic tunnel junction (MTJ), and exhibits an electrical resistance that depends on the magnetic state of the device. The memory elements are programmed by the magnetic field created from current-carrying conductors. Typically, two current-carrying conductors, the “digit line” and the “bit line”, are arranged in cross point matrix for programming of the memory element.
The interconnect stack is formed utilizing a number of vias and metallization layers. The via that electrically couples the interconnect stack to the memory element often is referred to as the MVia. Present day methods for forming MVias in an MRAM device often produce undesirable results and challenges. For example, the interconnect stack, including the MVia, is coupled to a digit line landing pad, which typically is formed at the same time the digit line is formed. However, known processes cause the MVia resistance to be high relative to the tunnel junction resistance. Note that the resistance is critical to the overall resistance of the device, of which only the resistance across the tunnel barrier is desirable. Other resistances in series detract from the raw MR of the device. With a filled via, the resistance can be low, if the filling material is very conductive, e.g., Cu. Another advantage is to improve the step coverage of the MTJ material in the via. However, a filled and polished layer, topped off with the bottom electrode, cannot be aligned to because the top layer is both opaque and completely planar.
Accordingly, there is a need for integrating vias within a magnetoresistive-based device which reduces series resistance, improve robustness to dielectric breakdown, allows alignment marks to be visible for subsequent processing, and provides placement of the bit line displaced from veils of the bottom electrode veils. Furthermore, other desirable features and characteristics of the exemplary embodiments will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.